A Combinatorial Approximation Algorithm for CDMA Downlink Rate Allocation

Abstract

This paper presents a combinatorial algorithm for downlink rate allocation in Code Division Multiple Access (CDMA) mobile networks. By discretizing the coverage area into small segments, the transmit power requirements are characterized via a matrix representation that separates user and system characteristics. We obtain a closed-form analytical expression for the so-called Perron-Frobenius eigenvalue of that matrix, which provides a quick assessment of the feasibility of the power assignment for a given downlink rate allocation. Based on the Perron-Frobenius eigenvalue, we reduce the downlink rate allocation problem to a set of multiple-choice knapsack problems. The solution of these problems provides an approximation of the optimal downlink rate allocation and cell borders for which the system throughput, expressed in terms of utility functions of the users, is maximized.

Optimal Joint Rate and Power Allocation in CDMA Networks

“…In [10], Perron-Frobenius theory is used to design an approximate algorithm for a model with multiple rates, which permits the use of techniques from convex optimization. In [4], the authors propose a polynomial time approximation scheme for the joint rate and power assignment problem under the assumption that the rates allocated are discrete and the power of the base stations is unlimited. Contribution and Outline.…”